Global warming and corresponding serious ecological and environmental problems induced by the rising CO₂ concentrations have attracted worldwide attentions. And they have become the focus of the international negotiations. As one of the core interface of terrestrial ecosystem, farmland soil in terrestrial ecosystems is the most intense part affected by human frequent disturbance. Management agricultural SOC is internationally recognized as one of the important strategies for mitigating or adapting global warming. Paralleled ridge valley of East Sichuan is typically representative of the concentrated distribution area of farmland around the Sichuan basin. It always plays an important role in the granary of East Sichuan. Recently, the production and management investment and frequent tillage disturbance in order to pursuit food security drove the opposite direction change of farmland SOC. Hence, it was very important to carry out the research on SOC dynamics. And, the farmland use of this region would be promoted to the strategic height responding to global change and food security at regional level. Taking Dianjiang County of Chongqing City is a typical area of East Sichuan parallel ridge valley, this paper analyzed the dynamics of farmland SOC of 0-20 cm soil layer and their driving factors during 1980-2011 by the soil type method, international general SOC density/storage calculation method and Stepwise Regression Analysis, using the second soil survey data in 1980 and the measured data in 2011. The results showed: (1)Farmland SOC density/storage of 0-20 cm soil layer during 1980-2011 in the study area overall presented slightly increased trend. Carbon increment per unit area reached to 2307.63 kg C hm^-2. Total content of carbon sink enhancement was 235945.83 t, with the increasing range of 10.74% and the average annual growth rate of 72.11 kg C hm^-2 a^-1. (2)The proportion of carbon sink, loss and relative balance area to the total area of this study area was 37.61:49.03:13.36. In general, the spatial patterns of farmland SOC sink showed that west and northwest part is higher than that south and southeast, and more than that northeast and southwest. (3) At macro level, the changes of farmland SOC density/storage was pronounced relationship to the distributions of soil type and their utilization practices. Especially, yellow soil and purple soil under different texture and different perturbations, showed the opposite carbon sink/source state.(4) At microcosmic level, the rank of factors obviously influencing SOC density average annual change rate was SOC density > N > C/N. Moreover, total N density and C/N ratio have positive effects on SOC density average annual change rate, the effects of SOC density initial value were negative function.(5)Results of this paper could provide scientific proofs for the effective management of farmland surface SOC carbon pool in the parallel ridge and valley area of East Sichuan, depending on appropriate inputs and suitable cultivation and management practices.